I have pushed the MultiBit master branch but noticed I made a slight mistake in build procedure.I built the 0.5.10 artifacts whilst on the release-0.5.10 branch, not master.You probably want to checkout that branch and see if you can reproduce the artifacts.

At the moment you cannot tweak the calculated fees.They are calculated as pretty much the minimum bitcoin-QT will accept.

Currently, as other software has not adjusted their fees downwards, when the network is busy you can get bumped to later blocks as the fee is a bit on the low side. I'm going to see how this develops - the fees people set create a feedback loop as to which transactions get in which block. (If you have a look at some of the posts I have put in the other alt clients threads this is explained more).

It might be necessary to add in something like a slider so that you can increase the fees above the minimum but I am hoping not to have to do that. Fees aren't something that a new user should have to worry about as it just adds to the learning curve for Bitcoin.

1) Currently the 'general' fee for a < 1KB tx in BitcoinLand is 0.0005 BTC. This is my estimate from having a look at the tx in the live stream on the blockchain.info home page.2) MultiBit 0.5.12, Andreas's Wallet v3.0.9 and Bitcoin-QT 0.8.2/3 have moved to lower fees of 0.0001 BTC for the first KB.3) Generally tx seem to get 'serviced' in order of creation but when there is a big gap between blocks the unconfirmed tx start piling up.4) Miners seem to be using a soft limit of 250 KB so they naturally put in the juiciest tx into their block. They clear about 600 of the tx from the unconfirmed pool for each block.

If the next block also takes an above average time to solve then the low-fee-tx can continue to get bumped by juicier tx that appear.

I have suggested to the other alt client devs that they have a *great* opportunity to save their users cash and drop their calculated fees to match the Bitcoin-QT fees. It is a bit of a Prisoner's Dilemma - I think Electrum tried to drop their fees to 0.0001 BTC / KB about a month ago but had to increase them again as no-one else did.

I think if/once most clients match the Bitcoin-QT fee structures the current soft limit on blocks will be sufficient - I think the miners are processing same-fee tx by age first (which effectively makes it first-transmitted-first-served).

It's a pretty interesting dynamic system the whole area of fees I must admit.

@ChooseusernameI am interested in why exactly you want to set a specific fee. Is the calculated one causing you problems ?

To make my transactions being processed fast in cause of %whatever_happened%, for example. And because it's my money and I want to control it by myself, not by algorythm. And at last because I can. So, I'll stick with 0.5.11, I guess. It's your program of course, and you choose how to develop it, but why make slider, why not just field pre-filled with automatically calculated fee which I can change? Why you disable me to change fees? I'm not a new user, I can worry about fees by myself.

@ChooseusernameI am interested in why exactly you want to set a specific fee. Is the calculated one causing you problems ?

To make my transactions being processed fast in cause of %whatever_happened%, for example. And because it's my money and I want to control it by myself, not by algorythm. And at last because I can. So, I'll stick with 0.5.11, I guess. It's your program of course, and you choose how to develop it, but why make slider, why not just field pre-filled with automatically calculated fee which I can change? Why you disable me to change fees? I'm not a new user, I can worry about fees by myself.

I appreciate what you are saying but it is just more complicated than that.

Say you increase the calculated fee. That needs paying for so you may need to bring in another tx input to spend. So now the tx is bigger. Maybe it needs MORE fee because it has slipped over a 1000 byte limit. So you try adding MORE tx inputs. But if you only have dust remaining in your wallet you can be worse off in that the tx inputs you just added are worth less than the extra fee you need to pay for adding them. You had a good tx with the smaller fee but cannot find a tx providing the increased fee.

Or maybe the new change amount you've created is under the new limit for small tx outputs - 5430 is it or is it 5340 satoshi ? Best write it down as you'll need to manually check that after you made the change to your fee - that small amount should get added to your fee to eliminate the small output. So you've eliminated a tx output so now the tx is smaller. So now you can possibly have a smaller fee to get the same effect as you had before you changed the fee. Do you want the option to rechange the fee a second time ?

Honestly have a look at the code I pointed to about calculating a fee.Of course it is your bitcoin but it is now impractical to work out the right fee manually.

A 'bad' fee means your tx either cannot be constructed (immediate fail), does not propagate (obviously bad but worse because then any change won't be spendable - very unpopular) or your tx takes ages to confirm (equally unpopular).

Sticking on 0.5.11 means you may create tx that don't propagate or take ages to confirm. It is your choice of course but my aim is to get people's transactions out in the network, propagated and confirmed as painlessly as possible for everyone.

Of course it is your bitcoin but it is now impractical to work out the right fee manually.

Sticking on 0.5.11 means you may create tx that don't propagate or take ages to confirm. It is your choice of course but my aim is to get people's transactions out in the network, propagated and confirmed as painlessly as possible for everyone.

No problem at all - I thought I would reply in detail as the technical details aren't at all obvious. Fees have become a little complicated and I expect they will change again in the future.

Bitcoin is an experiment after all !

I think you are right that there is still something missing though in that the user DOES want to change the fee sometimes according to the priority of the transaction. Simply having a computed value and not being able to change it does not feel right.

For instance if I am moving money around my own wallets/ amoungst friends it does not matter if it takes a little longer. But if I am in a coffee shop sending money to someone (eg localbitcoins) then I would probably increase the fees paid so that it will (almost certainly) get in the next block as we both save time. Or the payment might be important/ urgent for some other reason.

One of the parameters in the feesolver is "fee per kilobyte of transaction" so that seems like a good candidate for tweaking. It is hardwired at 0.001 BTC / KB at the moment but it might be worth making this something the user can set in the Preferences. Of course it is a little more work but that might be the way to go.

That way users still have control over what they want to set (tx urgency/ priority) but don't have to worry about all the fee rules.

@ChooseusernameI am interested in why exactly you want to set a specific fee. Is the calculated one causing you problems ?

To make my transactions being processed fast in cause of %whatever_happened%, for example. And because it's my money and I want to control it by myself, not by algorythm. And at last because I can. So, I'll stick with 0.5.11, I guess. It's your program of course, and you choose how to develop it, but why make slider, why not just field pre-filled with automatically calculated fee which I can change? Why you disable me to change fees? I'm not a new user, I can worry about fees by myself.

I appreciate what you are saying but it is just more complicated than that.

Say you increase the calculated fee. That needs paying for so you may need to bring in another tx input to spend. So now the tx is bigger. Maybe it needs MORE fee because it has slipped over a 1000 byte limit. So you try adding MORE tx inputs. But if you only have dust remaining in your wallet you can be worse off in that the tx inputs you just added are worth less than the extra fee you need to pay for adding them. You had a good tx with the smaller fee but cannot find a tx providing the increased fee.

Or maybe the new change amount you've created is under the new limit for small tx outputs - 5430 is it or is it 5340 satoshi ? Best write it down as you'll need to manually check that after you made the change to your fee - that small amount should get added to your fee to eliminate the small output. So you've eliminated a tx output so now the tx is smaller. So now you can possibly have a smaller fee to get the same effect as you had before you changed the fee. Do you want the option to rechange the fee a second time ?

Honestly have a look at the code I pointed to about calculating a fee.Of course it is your bitcoin but it is now impractical to work out the right fee manually.

A 'bad' fee means your tx either cannot be constructed (immediate fail), does not propagate (obviously bad but worse because then any change won't be spendable - very unpopular) or your tx takes ages to confirm (equally unpopular).

Sticking on 0.5.11 means you may create tx that don't propagate or take ages to confirm. It is your choice of course but my aim is to get people's transactions out in the network, propagated and confirmed as painlessly as possible for everyone.

Thanks for working on principled solutions that will elegantly handle the edge cases, jim618 :-)